1. Field of the Invention
The present invention relates to a superconductive coil system that is applicable to a product requiring a strong magnetic field.
2. Description of the Prior Art
In general, a superconductive coil system generates an intense electromagnetic force when it is energized, and hence in order to prevent deformation caused thereby, a strong restraining device is necessitated. Therefore, a superconductive coil system in the prior art was constructed as shown in FIGS. 4 to 6. More particularly, a superconductive coil 1 was constrained jointly with spacers 4 by surrounding the outer circumference of the coil with a coil retainer 2 of a stiffened cylindrical shell divided into upper and lower parts, and under the condition where comb teeth 5 of the upper and lower coil retainer parts had been meshed with each other, coupling pins 3 were inserted over the entire length of the coil retainer 2 to integrate the coil retainer parts.
However, the above-described superconductive coil system in the prior art involved the following problems to be resolved:
(1) The pins 3 for coupling the divided two parts of the coil retainer 2 are necessitated to be inserted over the entire length of the coil retainer 2. Therefore, if the size in the axial direction of the coil should become large, the coupling pins 3 would become extremely long and slender, hence workability at the time of inserting the pins 3 would become poor, and problems of seizure and the like would liable to occur.
(2) In order to insert the pins, fitting clearances between the pins 3 and the corresponding pin insert holes are necessary, but if the clearances are made large for the purpose of facilitating assembling, rattle is produced after assembly, an amount of deformation becomes large, and in some cases there is a risk of causing instability of the coil.
(3) Due to the electromagnetic force generated by the superconductive coil 1, upon the coupling portions of the coil retainer 2 is exerted a torque which appears as a tensile force on the side of the outer circumference, and two coupling pins 3 on the respective sides would bear the torque, but since the coupling pins 3 are positioned between the inner surface and the outer surface of the coil retainer 3, the moment arm of the torque is short, hence a load applied to the coupling pin 3 would become large, and the size of the product would become large.